Valve for changing over the heat flows of a heat pump, taking into account the flow direction reversal in a heat exchanger connected during heating operation to the source side of the heat pump

ABSTRACT

A valve arrangement includes a changeover valve having a housing ( 7 ) with at least four connection pieces ( 8 ) connected to a heat pump and at least four additional connection pieces ( 9 ). At least two of the additional connection pieces are connected to a heat source and at least two of the additional connection pieces are connected to a heat sink. At least one valve body ( 10 ) is associated with a drive element for moving the valve body relative to the different connection pieces in the housing. A heat exchanger ( 2 ) is connected during heating operation to the source side of the heat pump, in which a flow direction reversal of the heat transfer medium can be generated when there is a changeover between heating operation and cooling operation.

The present invention relates to a valve arrangement for operating a heat pump in different ways by means of changing over the heat flows according to the preamble of claim 1 as well as a method for operating a heat pump in different ways.

Buildings can be both heated and cooled by heat pumps. The changeover from the heating mode to the cooling mode of the building can be generated in different ways, but requires an active shift either inside the heat pump or outside the heat pump at the hydraulic connections. Only by means of this shift it is possible that, e.g. during cooling operation, heat can be withdrawn from the building, where before, during heating operation, heat was released.

In typical heat pump devices as well as in widespread air conditioners, which are designated for heating and cooling operation, the changeover takes place within the heat pump cycle. Thereby the heat pump changes the operating mode by turning the vaporizer into the condenser and the condenser into the vaporizer. This kind of changeover is not ideal and leads to efficiency losses in one of the two operating modes because the components vaporizer and condenser are not identical. Moreover, the cooling medium cycle becomes more complicated by additional valve equipment, which is necessary for the changeover.

Due to the mentioned disadvantages, it is desirable to use different possibilities for the changeover. A further possibility is leaving the heat pump cycle unchanged but interchanging the heat source and heat sink on installation side during the switching of an operating mode, e.g. from heating to the other mode, e.g. to cooling, as described in DE 2542728 A1, for instance. However, the mentioned interchange leads to a mixing of the media between heat source and sink. Therefore, the mentioned manner of outside changeover is only suitable, when the same medium is used on source and sink side. Thus, e.g. air-water and brine-water heat pumps, are excluded, unless additional heat exchangers are used, which prevent the mixing of the media.

Heat pump devices built nowadays are often operated with geothermal probes. Due to the natural temperature gradient prevailing in moderate climatic zones, it is interesting for the heating by means of heat pumps to use deep geothermal probes>300 m for efficiency reasons. For the nowadays standardly used U-shaped/double U-shaped tubular probes, the pressure loss for media circulation is considerable for such great depths.

Moreover, for this type of probe, a thermal short-circuit occurs so that the potential of deep geothermal probe drills cannot be used to full capacity. As alternative probe types, e.g. so-called coaxial geothermal probes may be appropriate. In such probes the heat transfer medium flows through both an external tube and an internal, ideally thermally isolated, central tube with a smaller diameter. For better usage of the potential of high temperatures during heating operation of the heat pump, the de-heated heat transfer medium flows in the geothermal probe inside the external tube into the depth and is warmed up continually. At the end of the geothermal probe the maximum temperature is reached and the heat transfer medium flows inside the internal central tube back to the heat pump. During cooling operation of the heat pump, heat source and sink are interchanged and the flow direction in the geothermal probe is reversed. Thereby, the heat to be led away from the condenser of the heat pump is returned at maximum temperature and at the deepest point of the geothermal probe to earth and stored there effectively. The warmed-up heat transfer medium thus flows downwards inside the central tube and backwards inside the external tube. The flow direction reversal of the heat exchanger connected during heating operation to the source side of the heat pump during a changeover between heating operation and cooling operation is subsequently explained in more detail in connection with FIG. 1.

The changeover of the heat flows on the installation side, instead of the cooling medium changeover in the heat pump, is nowadays applied only rarely and with valve types (4-way, 3-way, stop valve, etc.) available today, such changeover manners result in an extensive hydraulic system with at least 2 single valves for simple changing over heating/cooling, at least 3 valves for changing over including flow direction reversal of the geothermal probe and a high number of connections, which come along with high installation expenses and corresponding costs. The increased material and installation expense for implementing the outer changeover and the additional flow direction reversal limit the spreading of this solution. For this reason, there is a need for technical solutions for changing over the heat flows including flow direction reversal, which solutions are simple and come along with a reduced material and installation expense.

A possible solution, such as described in EP 0 967 447 A1, causes the interchange of heat source and sink with one single valve, but does not cause a flow direction reversal in a, e.g. connected coaxial geothermal probe. Therefore, it is an objective of the present invention to propose a possibility for changing over the heat flows with a flow direction reversal in a heat exchanger connected during heating operation to the source side of the heat pump, such as a geothermal probe, and which solution is simple and possible with a reduced material and installation expense.

The main idea of the present invention is, as also described in EP 0 967 447 A1, to obtain with one single valve a simple outer changeover for heat pumps, which use the same liquid medium both on the source and the sink side.

The valve should be formed such that, in different embodiments along with the simple changeover of the source and the sink side also a flow direction reversal can be effectuated in a geothermal probe, for instance. Moreover, the valve shall give the possibility, where required, to bypass the heat pump, to short-circuit directly the source and sink side and to allow, e.g. in combination with a geothermal probe, a direct cooling, so-called “free cooling”, of the building and/or a direct regeneration of the earth, e.g. with a thermal collector.

According to the invention, a valve arrangement is suggested for operating a heat pump in different ways, like for changing over the heat flows of a heat pump, according to the wording of claim 1.

It is suggested that the valve arrangement comprises a changeover valve and a heat exchanger. The changeover valve having a housing with at least four connection pieces connected to the heat pump as well as at least four connection pieces, at least two of which are connected to a heat source and at least two of which are connected to a heat sink, with at least one valve body and a drive element for moving the valve body relatively in relation to the different connection pieces in the housing. The heat exchanger is connected to the valve such that the heat exchanger during heating operation of the heat pump is connected to the source side of the heat pump and that during the changeover of the heat pump between heating operation and cooling operation the flow direction of the heat transfer medium in the mentioned heat exchanger is reversed. As heat exchanger, a coaxial geothermal probe can be used, for example.

According to an embodiment, it is suggested that the valve body of the changeover valve shows penetrations like hollowly shaped passages, of which at least a part connects at least two connection pieces in the housing in different ways to each other according to the operating mode.

According to an embodiment, it is suggested that the valve body is designed rotationally symmetrical, for instance cylindrical or spherical, and is rotatable in relation to the housing surrounding the valve body shell-like for connecting the connection pieces to each other in different ways.

According to a further embodiment, it is suggested that the valve body is linearly movable in relation to the housing, whereby the connection pieces are connectable to each other in different ways according to the operating mode by means of a translational movement. Further embodiments of the invention are characterized in the dependent claims.

Furthermore, a method for operating a heat pump in different ways by changing over the heat flows of the heat pump according to the wording of claim 11 is suggested.

Further embodiments of the method according to the invention are characterized in the dependent claims.

The invention is now further explained by referring to the attached figures showing exemplified embodiments.

FIGS. 1a and 1b show an example of a hydraulic connection of a heat pump system having the valve arrangement according to the invention;

FIG. 2 shows a schematic sectional view of a changeover valve according to the invention having a connected heat exchanger, which is connected to the source side of the heat pump during heating operation;

FIGS. 3 and 4 show two exemplary embodiments of the changeover valve according to the invention in a schematic sectional view, also having a connected heat exchanger, which is connected to the source side of the heat pump during heating operation;

and FIG. 5 schematically shows different operating modes having connections between the different connectors of the changeover valve and the flow direction of the connected heat exchanger, which is connected to the source side of the heat pump during heating operation.

FIGS. 1a and 1b show an example of a hydraulic connection of a heat pump system having a heat pump 1, a coaxial geothermal probe 2, a thermal collector 3, a room releasing system 4, circulation pumps 5 and a valve device 6 of the valve arrangement according to the invention.

FIG. 1a shows the system during heating operation, FIG. 1b shows the system during cooling operation, respectively, with exemplary operation temperatures each. During heating operation the cycle of the thermal collector is switched off and the coaxial geothermal probe is flowing from outside to inside (from α to β). During cooling operation the cycle of the collector is switched on, the flow direction inside the coaxial geothermal probe is reversed and the flow takes place from the inside to the outside (from β to α). The reversal of the flow direction prevents selectively and favors selectively, respectively, the heat transfer between the probe fluid and the earth alongside of the probe length.

The outer changeover allows a constant and concordant operation of the cooling cycle of the heat pump and increases thereby the average efficiency of the heat pump analyzed over both operating modes, heating and cooling.

The invention reduces the complexity of the hydraulic installation, which results from the outer changeover with flow direction reversal using classic valve technique, by situating the complexity of connections in one single valve. Therefore, the installation expense is reduced and there is the potential to realize an advantageous solution. The reduction from at least three 4-way or four 3-way valves for changing over heating/cooling including the reversal of the flow direction in the probe to one single valve improves by means of saving space also the possibility for integrating the outer changeover into the housing of the heat pump.

Furthermore, the changeover valve of the valve arrangement allows a simple integration of additional features, such as bypassing the heat pump for a “free-cooling” mode or for direct regeneration of the earth using a thermal collector or the interchange of the order of the flow of the geothermal probe and the thermal collector in connection to a flow direction reversal of the coaxial geothermal probe or others.

According to the invention, the changeover valve of the valve arrangement, as show in FIG. 2, comprises a housing 7 having connection pieces for the heat pump 8 and for the sources/sinks 9, a valve body 10 and a drive element 11 with possible extensions of the connection pieces for connecting directly, e.g. a thermal collector.

The valve body 10 comprises cavities, penetrations, respectively, which connect the connection pieces of the heat pump side 8 in a special way to the connection pieces of the source/sink side 9. Which connection pieces are connected to each other depends on the operating mode (heating/cooling, “free cooling”, regeneration earth, etc.). Moreover, in opposite to the illustration in FIG. 2, it is possible that the connectors of the heat pump and of the source/sink side can be arranged both-sided each at the valve body. If need be, the connectors can be arranged all-sided.

For the valve arrangement, as shown in FIG. 2, different embodiments are possible for changing over the heat flows according to the described invention. Two possible embodiments are changed over by a rotative movement around the x-, y-axis, respectively, and based on a cylindrical valve body having penetrations on the shell surface, or on the front sides, respectively. Further rotationally symmetrical geometries, such as a ball, are conceivable as valve bodies as well. A further embodiment is based on a linear slider, which causes the changeover by means of a movement translational along the x-axis or transverse to the x-axis.

It is characteristic for the invention that the outer changeover and the flow direction reversal takes place in a heat exchanger connected during heating operation to the source side of the heat pump, such as a geothermal probe, within one single element (valve) and that only one adjusting element is necessary for the changeover. As alternative embodiment to the embodiment shown in FIG. 2, the connections of the connectors can also be defined in the housing 7 and, instead of the valve body 10, a simple control disk can also be used, which selectively releases certain connections in the housing and separates others.

In FIG. 3 and FIG. 4, two exemplary embodiments of the valve arrangement according to the invention are shown. The changeover valve, as component of the mentioned valve arrangement, is shown in a sectional view, on the one hand, as cylinder with rotation around the x-axis (FIG. 3) and, on the other hand, as axial slider with movement along the x-axis (FIG. 4). The heat exchanger, which is connected during heating operation to the source side of the heat pump, is connected to the changeover valve in both embodiments. In both embodiments a changeover takes place between the source and the sink side as well as the flow direction in the connected heat exchanger is reversed.

The position of the cylindrical changeover valve shows the heating operation in FIG. 3, above, so that i is connected to A, ii to C, iii to B and iv to D. The connected heat exchanger is flown through from connector α in direction to connector β. During cooling operation (FIG. 3 below) the connectors are connected to each other as follows: i to C, ii to A, iii to D and iv to B. The connected heat exchanger is flown through from connector β in direction to connector α.

In FIG. 4 above, the valve is shown in the axial embodiment in the position for the heating operation, so that also i is connected to A, ii to B, iii to C and iv to D. In this embodiment, the connection between iv and D during heating operation is not only achieved by the valve body but by the valve body and the housing cavity. The connected heat exchanger is flown through from connector α in direction to connector β. During cooling operation (FIG. 4 below), the connectors are connected to each other as follows: i to B, ii to D, iii to A and iv to C.

The connections between the heat pump and the source/sink during cooling operation are achieved again alone by the valve body for the shown arrangement. The connected heat exchanger is flown through from connector β in direction to connector α.

Exemplary illustration of the connection between the heat pump and the source/sink side, as well as flow direction of the heat exchanger connected during heating operation to the source side of the heat pump for different operating modes.

In FIG. 5, both the connections between the different connectors of the valve device for different operating modes and the flow direction of the connected heat exchanger, are schematically shown. For the outer changeover of the source and sink side including flow direction reversal (FIG. 5, position a-c), the heat pump, the release system and a heat exchanger (e.g. geothermal probe) are connected to the valve device. In case of a possible extension of the valve device, a thermal collector is connected additionally to the valve device (FIG. 5, position d-f). By means of the said extension it is possible to maintain the order of the flow of the geothermal probe and the thermal collector, or to interchange the order during simultaneous reversal of the flow direction inside the geothermal probe, respectively.

The different operating modes in FIG. 5 are the following:

-   Position a: Heating -   Position b: Cooling with reversal of the flow direction in the     geothermal probe -   Position c: Free cooling -   Position d: Possible extension; heating with thermal collector and     coaxial geothermal probe -   Position e: Possible extension; cooling with thermal collector and     coaxial geothermal probe -   Position f: Possible extension; regeneration of the earth with     thermal collector

Explanation i Condenser OUT ii Vaporizer IN iii Vaporizer OUT iv Condenser IN A Room VL

B Heat exchanger connector α C Heat exchanger connector β

D Room RL

E VL thermal collector F RL thermal collector

Both the possible embodiments of a valve arrangement, according to the invention depicted in FIGS. 1 to 5, and the described methods are of course only examples for a better understanding of the present invention.

In particular, the shown valve arrangements are only examples and other embodiments are possible. For instance, it is conceivable that the valve body is formed as ball and that by means of rotating the valve body inside of a shell-shaped housing surrounding the body, the different connectors can be connected to each other as shown in FIG. 5. Instead of a slider, a cylinder can of course be moved linearly inside of the housing and, where required, parts of the connections can already be designated inside the housing. A solution as linear slider, which is slid transverse in relation to the x-axis and comprises in the valve body respectively per position penetrations corresponding to the number of outer connectors, is also conceivable. The present invention does not especially emphasize on the material choice for producing housings and valve bodies, since metallic materials as well as polymer, ceramic or other materials can be used depending on the requirement. The present invention does neither especially emphasize on the controlling of the valve, since the possibilities are endless. 

What is claimed is:
 1. A valve arrangement comprising a changeover valve having a housing (7) with at least four connection pieces (8) connected to a heat pump, with at least four connection pieces (9), at least two of which are connected to a heat source and at least two of which are connected to a heat sink, with at least one valve body (10) and a drive element for moving the valve body relative in relation to the different connection pieces in the housing and further comprising a heat exchanger (2) connected during heating operation to the source side of the heat pump, in which a flow direction reversal of the heat transfer medium can be generated when there is a changeover between heating operation and cooling operation.
 2. The valve arrangement according to claim 1, characterized in that the valve body (10) comprises penetrations or hollowly shaped passages, of which at least a few connect at least two connection pieces to each other in different ways according to the operating mode.
 3. The valve arrangement according to claim 1, characterized in that the valve body is designed rotationally symmetrical, like cylindrical or spherical, and is rotatable in relation to the housing surrounding the valve body for connecting the connection pieces to each other in different ways.
 4. The valve arrangement according to claim 1, characterized in that the valve body is movable linearly in relation to the housing, whereby the connection pieces are connectable to each other in different ways according to the operating mode by means of a translational movement.
 5. The valve arrangement according to claim 1, characterized in that the drive element is formed by a mechanical drive, wherein the controlling is carried out manually or based on e.g. electrical energy.
 6. The valve arrangement according to claim 1, characterized in that at least two connectors are designated for a condenser, at least two connectors for a vaporizer, at least two connectors for a cooling or heating cycle, respectively, and at least two connectors for a heat source/sink and/or a heat store device, such as a geothermal probe.
 7. The valve arrangement according to claim 1, characterized in that the connection pieces are connectable in different ways such that the heat source and sink of the heat pump are interchanged and thereby allow both heating and cooling operation.
 8. The valve arrangement according to claim 1, characterized in that the connectors are connectable such that the connection pieces of the heat source and heat sink are directly connectable to each other.
 9. The valve arrangement according to claim 1, characterized in that further connectors in the housing are designated for connecting accessory devices like thermal collectors, further cooling or heating cycles, heat stores, etc.
 10. A heat pump system having a heat pump, a coaxial geothermal probe, a room releasing system, circulation pumps and, where required, a thermal collector with a valve arrangement according to claim
 1. 11. A method for operating a heat pump in different ways by changing over the heat flows of a heat pump, as well as for generating a flow direction reversal in a heat exchanger connected during heating operation to the source side of the heat pump, characterized in that the heat pump is connected to a housing of a valve arrangement by at least four connectors, as well as at least one heat source and at least one heat sink are also connected to the same housing by at least two connectors each and the different operating mode is carried out by connecting the connectors to each other in different ways by means of a valve body located in the housing, the valve body being moved in relation to the housing.
 12. The method according to claim 11 for heating or cooling a building by use of at least a heat source/heat sink each, such as a heat absorption/heat release system, as well as a geothermal probe, characterized in that the connectors of the heat pump and the heat source/heat sink are switched by means of the penetrations or hollowly shaped passages of the valve body such that a different usage of the heat pump (heating/cooling) is possible without reversal of the inner cooling medium flows.
 13. The method according to claim 11, characterized in that a reversal of the flow direction is generated by connecting the connectors in different ways, in particular in a coaxial geothermal probe.
 14. The method according to claim 11, characterized in that by arranging further connectors under usage of one or more thermal collectors by connecting the connectors in different ways, the perpetuation of the order of the flow of thermal collectors and geothermal probe is possible, where required, during simultaneous flow direction reversal of the geothermal probe. 